The Principle Operation of a Laboratory Faucet Dual Check Vacuum Breaker – Backflow Prevention Device – Installation Considerations

The LFDC is designed to be installed downstream of the shut-off on a laboratory faucet. The LFDC is recommended for laboratory faucets and is not suitable for continuous pressure applications. Continuous pressure shall mean twelve (12) hours of use in a twenty-four (24) hour period. The LFDC should not be installed where the water would be corrosive. Corrosive water conditions could render the product ineffective for the service intended. The LFDC shall be installed where water spillage from the atmospheric vent will not cause water damage to the immediate area. The LFDC is suitable for supply pressure up to 150 psi. The LFDC is suitable for hot and cold water applications and has a temperature range of 33 degrees F to 180 degrees F. The LFDC can be installed horizontally or vertically. Install the LFDC in the line with the arrow on valve body pointing in the direction of flow. Before installing, flush out pipe lines to remove scale and other foreign matter. Downstream shut-off valves should not be utilized unless there is a means for stopping the flow of water upstream of the LFDC and the downstream pressure can be released. The LFDC shall not be installed inside a wall or any concealed location since annual inspection of the LFDC is required and necessary. Regular inspection, testing and cleaning assures maximum life and proper product function. The LFDC can be installed on new or existing lab faucets with no pluming changes. The LFDC is designed for average flow rated and low pressure losses. At zero gpm, the pressure loss is approximately 4 to 5 psi. The pressure loss in a no-flow state is created by the force loading of the check valve springs and atmospheric vent diaphragm. At 3 gpm, the pressure loss is approximately 12 to 14 psi. This pressure loss in a flow state is created by the loading of the check valve springs being forced open, the atmospheric vent diaphragm being forced closed, and friction loss as water is flowing through the LFDC. Consult the manufacture literature for pressure losses flow rates.